I have both balls with the same surface prep and layout. I am not sure either would be my first choice at Nationals, but I like the Paradox better on flatter patterns than the Lock. Both balls hit very well for me, but the Lock wants to go a little bit sideways too much off the end of the oil, and tends to over under when the heads break down. I definitely would not use either in box condition. Whatever you go with I think the big thing is not to get too aggressive with the surface. I know that teams got a lot of publicity for going in to the team event and trying to blow a hole in the patterns with super aggressive shells, but I don't think that is the best strategy with the Ice oil.
If you are looking for something really aggressive in the Storm line, I would look at the Alpha Crux over the Lock. Crux is very strong, but gets into a better roll for me than the Lock.
